Arrays of biological tissue can be created by removing cores from regions of interest in a series of donor blocks of embedded tissues. The cores removed are placed in a regular array in a recipient block. This is typically done with two different punches, one for obtaining the cores of interest and the other for creating the receiving holes in the recipient block. The present invention comprises such a system including two separate z axes, one for each punch. Each punch has its own stylet and the axis of each punch is parallel to the axis of its drive.
Biological tissue arrays consist of regular arrays of cores of embedded biological tissue arranged in a sectionable block typically made of the same embedding material used originally for the tissue in the cores. The new blocks may be sectioned by traditional means (microtomes etc.) to create multiple nearly identical sections each containing dozens, hundreds or even over a thousand different tissue types. These sections may be used for histochemical and other assays. Any test performed on any one of these sections is effectively performed on hundreds of samples at once. The result is a tremendous saving in effort and time and some increase in the availability and precision of control samples.
Tissue arrays have been constructed entirely manually (Battifora, H., xe2x80x9cThe Multitumor (sausage) tissue block: novel method for immunohistochemical antibody testing,xe2x80x9d Laboratory Investigation Vol. 55, pp. 244-248, 1986) and with the assistance of mechanical mechanisms (Kononen et al xe2x80x9cTissue microarrrays for high-throughput molecular profiling of tumor specimensxe2x80x9d, Nature Medicine Vol.4 Number 7 July 1998 pp. 844-847) for a variety of biological applications.
A manual instrument has been described in U.S. Pat. No.6,103,518 (Leighton) entitled xe2x80x9cInstrument for constructing tissue arraysxe2x80x9d. Semiautomatic systems have also been proposed. The manual methods have largely been superceded by those aided by instruments due to the speed, precision and increased density of the latter. In these devices, two hollow needle-like punches are used, one slightly smaller than the other to create a hole in a recipient block, typically of paraffin or other embedding medium. The larger punch is used to obtain a core sample from a donor block of embedded biological tissue of interest.
The punches are sized such that the sample obtained just fits in the hole created in the recipient block. Thus the sample is a snug fit in the recipient block and a precise array can be created.
The recipient block is held in an appropriate fixture during the entire processxe2x80x94although it may be removed and be alternated with one or more other recipient blocks to create more than one array from one set of donor blocks. Micrometer drives or other precision linear positioning means position the punches with respect to the recipient block or the recipient block with respect to the punches. It is clearly desirable that the donor punch reach exactly the same x,y position that the recipient punch reaches on the recipient block for a given setting of the micrometer drives. If it does not, the retrieved sample will not pass smoothly into the hole just created for it, but instead will be damaged or lost. It is further desirable that this motion be created reliably and inexpensively.
In a co-pending application in which the present inventor is a co-inventor, it is taught to use slides and drive mechanisms to first move the recipient punch into a central position and alternately, the donor punch. This mechanism is cumbersome, expensive, slow and prone to misalignment errors. The use of slides at an intermediate angle such as 45 degrees, as taught in this application is particularly problematic, as small errors in height positioning can lead to corresponding errors in lateral position and vice versa. In other prior art (Leighton), a turret or other means allows the two punches to share a single z axis slide or drive. This mechanism is appropriate for a simple, manually operated instrument, but awkward for an automated instrument in which all motions are driven by powered actuators (pneumatic, electric etc.). Special mechanisms must be machined and assembled, and standard components are not available. It must be noted in all of the prior art it was taught that the two different punches should be brought to the same position with respect to the laboratory frame of reference as well as with respect to the pallet holding the donor and recipient blocks with a dedicated mechanism and without the use of the xy drives that might be present for moving to successive locations. Apparently the primary goal of putting the donor cores in the same holes that had been created by the recipient punches blinded the prior inventors to the possibility of doing this at two different locations. It may also have been thought that the x-y drives were not accurate enough to guarantee that correct alignment could be obtained.
It is the purpose of the present invention to overcome the cumbersome quality and slow speed of the prior art and to provide a simple precise means of alternately positioning the two punches in any tissue array instrument. In addition, it is the purpose of the present invention to provide a means for constructing a robust automated instrument.
The invention comprises completely separating the two punches (donor and recipient), giving each their own stylet (unlike the above-described device) and each their own z-drive (unlike Leighton). The x and y drives that must be present to bring different areas of the donor and recipient blocks into position under the punches in any arrayer can be simply programmed with appropriate offset values to position the point of interest under either punch in turn as required.
Since this offset value is now used in the control, it may also be used for a further improvement: The positions of the tips of the two punches can be periodically measured automatically by sensors mounted on the same pallet as the donor and recipient blocks. Whenever their positions may have moved (perhaps due to encountering a more dense block or irregularity, or perhaps by being disturbed by an operator or foreign object, or simply being altered by virtue of a new punch being installed) then the new positions can be measured and automatically used to update the offset value. This novel combination of
a) sensing the tip positions with a sensor mounted on the block holding pallet with
b) two different z drives allows a system to be constructed with standard components and to be robust in the face of environmental challenges and mechanical drift.
Each z drive moves its respective punch in line with the axis of the punch. Firstly, each drive can move its punch completely out of the way of the recipient and donor blocks, for example when the other punch is being used or when the x and or y drives are being used to move different points on the blocks under the punches or for observation. Secondly, each drive can move its punch to just contact or nearly contact the surface of a block, for example for depositing a donor core into a recipient block. Thirdly, each drive can move its punch into the blocks, for example for obtaining and removing a blank core from a recipient block or a tissue core from a donor block.
Since each of the two drives can move its punch into and out of the way as well as to cause it to touch or penetrate the appropriate block, only two drives are required for two punches. In the co-pending application in which the present inventor is co-inventor, four drives are required, two for moving the two punches into and out of position, and two for moving the punches into and out of the blocks. In Leighton, manual operation is contemplated, but were the system to be automated, two drives would be required, but they would need to be of two different types, one for toggling the turret from one position to the other, and another for moving the turret up and down. This would result in greater costs, as two different types of drives would be required to be designed and manufactured for the two different types of motion. In the present invention, the two drives can be identical, leading to reduced costs and simplicity.
It is within the scope of this invention to use more than two punches, each with its own drive, for example to permit quick changes between different sizes of punches for different applications.
The rest of a system using this improvement may be similar to that already described in the prior art. For example, powered or manual micrometer drives or the like may be used to position the punching mechanism over the blocks or the blocks under the punching mechanism. A removable bridge may be used for supporting the donor blocks over the recipient blocks, or the donor blocks may be attached to the same pallet that holds the recipient blocks. The latter arrangement allows the same x and y drives and slides to be used for both donor and recipient blocks.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood, and so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter, which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other tissue arrayers for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent structures do not depart from the spirit and scope of the invention as set forth in the appended claims.